The first study in the UK to directly compare immune reactions between Pfizer's and AstraZeneca's COVID-19 vaccines has found strong and broadly similar antibody responses in people aged over 80 after a first dose of either shot, Reuters news agency revealed on Wednesday.

The study analysed blood samples from 165 people in Britain aged between 80 and 99 who had been given a first COVID-19 vaccine dose.

Scientists who carried out the study also found that T cells, a critical component of the immune system, showed a more enhanced response in those who received the AstraZeneca/Oxford University vaccine compared to those who were given the Pfizer/BioNTech vaccine. The scientists believe that these findings merit further investigation.

Reuters added that this study was published online as a preprint before being peer reviewed. It found that key antibodies were present and at similar levels in 93% of the 76 study participants who were given the Pfizer single COVID-19 vaccine dose and 87% of the 89 participants who received the AstraZeneca shot.